Heretofore, a prior art slit trenching and cable laying device, such as that shown in the prior U.S. Pat. No. 3,685,591 included a frame on which was mounted a relatively movable plow for digging a slit trench and laying a cable or line in the trench. The prior art plow usually had a digging motion confined to a vertical plane. In certain soil conditions, such as heavy clay or moisture, considerable power was needed to operate the plow since large surface areas on both sides of the plow were in contact with both sides of the trench. The large area surfaces in contact created large drag forces which could stall the plow or slow its operation.
In the past one approach to overcoming this problem was to provide the device with its own powerful engine. While the large engine did, to some degree, alleviate the drag problem, it created its own disadvantages, such as increasing the cost, bulk and weight of the device. Further, because of its large bulk and weight such device usually operated at only one trench depth, it being difficult and expensive to provide means to alter the operating depth. Of course such device had the disadvantage of not digging the minimum depth trench necessary on each application.